std:: ptr_fun

Creates a function wrapper object (either std:: pointer_to_unary_function or std:: pointer_to_binary_function ), deducing the target type from the template arguments.

This function and the related types are deprecated as of C++11 in favor of the more general std::function and std::ref , both of which create callable adaptor-compatible function objects from plain functions.

Parameters

Return value

A function object wrapping f .

Exceptions

May throw implementation-defined exceptions.

Example

#include <algorithm>
#include <functional>
#include <iostream>
#include <string_view>
 
constexpr bool is_vowel(char c)
{
    return std::string_view{"aeoiuAEIOU"}.find(c) != std::string_view::npos;
}
 
int main()
{
    std::string_view s = "Hello, world!";
    std::ranges::copy_if(s, std::ostreambuf_iterator<char>(std::cout),
        std::not1(std::ptr_fun(is_vowel)));
#if 0
// C++11 alternatives:
        std::not1(std::cref(is_vowel)));
        std::not1(std::function<bool(char)>(is_vowel)));
        [](char c) { return !is_vowel(c); });
// C++17 alternatives:
        std::not_fn(is_vowel));
#endif
}

Hll, wrld!

See also